Modified organic fluids of the glycol type and methods of producing the same



United States Patent "cc MODIFIED ORGANIC FLUIDS OF THE GLYCOL gYPE ANDMETHODS OF PRODUCING THE No Drawing. Original application Mar. 5, 1957,Ser. No. 643,923. Divided and this application Nov. 24, 1958, Ser. No.775,699

6 Claims. (Cl. 252-75) This application is a division of our applicationSerial No. 643,923, filed March 5, 1957, for Modified Organic Fluids ofthe Glycol Type and Methods of Producing the Same.

This invention relates to methods for improving the physical and/orchemical properties of organic fluids such as glycols and ethers ofglycols, and to the compositions produced thereby. It especially relatesto org'anic compositions of this type in a form for use as additives tosimilar or other organic fluid compositions for obtaining one or more ofthe improved properties and in desired degree. -Glyco1s and ethers ofglycols and mixtures of either or both are widely used, for example, ashydraulic fluids, as heat exchange fluids, for instance cooling fluidsfor internal combustion engines, and for like and other purposes. It iswell known that corrosion of metals by these fluids is a problem andthat such corrosion by many organic fluids including certain of theseglycols such as ethylene, diethylene, propylene, dipropylene andtriethylene glycols can be to some extent buffered or inhibited bydirectly adding thereto a minor proportion of an alkali metal oralkaline earth metal borate which must be soluble in the glycol, such assodium or calcium tetraborate in the'form of a solid decahydrate orpentahydrate, i.e., a borate having water of hydration.

However, such known procedures have the serious disadvantage ofintroducing an appreciable amount of water of hydration into theresultant composition which is part of the formulation but active asfree water. Such water of hydration in undesirable under many practicalconditions of use. In particular, such water-of hydration tends toincrease the vapor pressure of the organic fluid composition and tolower its boiling point, both of which are serious disadvantages whenthe organic fluid composition is to be used under conditions of hightemperature because they contribute to causing vapor lock. Moreover,such water of hydration when in the vapor phase may itself causecorrosion to certain metals when brought into intimate contacttherewith. In addition, there are many organic fluids such as ethers ofglycols in which the aforesaid borates, as such, are either insoluble ormay form insoluble complexes and which have not heretofore lentthemselves to direct borate treatment. Furthermore, in the case ofhydraulic fluids which normally are constituted of a mixture of glycoland ethers of glycol, the known procedures for adding borate to thefluid have required the use of such large amounts of glycol that theviscosity of the resultant hydraulic composition may be adverselyaffected by an increase thereof at low temperatures. Also the volatilityof the composition may be adversely'increased at high temperatures andsuch composition may effect a volumetric change in rubber with which itcomes in contact.

A primary purpose of the present invention is to make possible new andimproved organic fluid compositions Patented May 2, 1961 avoiding one ormore of the above ditliculties and which may be of improvednon-corrosive character and to produce such improved compositions in aform suitable as additives to conventional organic fluid compositionsfor imparting their improved physical and/or chemical prop ertiesthereto.

Another broad purpose of the present invention is to provide suitablemetallic organic additives for organic fluids which are useful whereveralkalinity or buflering action is required to thereby improve thephysical or chemical properties of such organic fluids.

A related object is to provide a process for treating glycols of thetype of ether glycols and hexylene glycol in which a borate is normallyinsoluble or only slightly soluble, in a manner to obtain a substantialconcentration of borate therein.

A more particular object of the invention is to provide a liquid boratecomplex that may conveniently be added to organic fluids of thedescribed types to provide them with improved corrosion inhibitingproperties. These corrosion inhibiting liquid compositions of theinvention will be directly miscible in all useful proportions with manyorganic fluids, including in particular glycols, ethers of glycols andmixtures of either or both, of the type ordinarily used for hydraulicfluids, anti-freezev cooling fluids for internal combustion engines, andlike and other purposes.

A further object of our invention is to provide a glycol additive highin borate concentration which maybe added to an organic fluid such as anether of glycol to form a functional hydraulic fluid without adverselyaifecting the viscosity of the functional fluid at relatively lowtemperatures, without adversely affecting its volatility at hightemperatures, and which will control the rubber swelling characteristicsof the functional fluid.

Still another object is to provide a process of obtaining suitableconcentrations of borate in a mixture of organic fluids including aglycol and without effecting a substantial loss of glycol byevaporation.

A specific object is to provide a glycol-borate con-' densation complexfrom which the water of hydration of the borate reactant has beensubstantially or entirely removed.

Another specific object is to provide a glycol-borate Other objects andadvantages of the invention will appear as the description progresses.

When the compositions of the invention are used as additives for organicfluids, they will preferably contain a relatively high concentration ofborate, the extent of which will be determined by the application forwhich the additive is intended. Typically this may be between about 3 toabout 40% by weight. The higher the concentration, the correspondinglymore effective will the additive be and correspondingly lesserproportions of the additive will be required for making up a finalworking composition. For example, where effective resistance tocorrosion is desired, a concentration of about 15% tmabout 35% of theborate is a desirable range for a practical and economical additive. Itwill be understood, however, that such concentrations may be increasedor decreased. In fact the concentration may be such that the additiveitself may constitute the final or working composition although forreasons of evaporation hereinafter noted, such is not preferred.

We have discovered that tetraborates and metaborates 3 of the alkalimetals and of the alkaline earth metals can be caused to react withglycols containing from 2 to 6 carbon atoms, for example, ethyleneglycol [HCH CH OH] diethylene glycol (di-2-hydroxyethyl ether) [HOCH CHOCH CH OH] triethylene glycol [HOCH CH OCH CH OCH CH OH] propyleneglycol (1,2-propanediol) [CH CH(OH)CH OH] hexylene glycol(2-methyl-2,4-pentanediol) [CH C0H(CH )CH CHOHCH 2,3-butanediol [CHCHOHCHOHCH 1,4-butanediol [CH OHCH CH CH OH], and with commercialmonoalkyl ethers of such glycols (the alkyl group of the monoalkylethers containing from one to four carbon atoms) containing a glycol asa diluent and with which the borate may react, to form condensedproducts with release of water of hydration and/or of condensationdepending upon the conditions of the reaction and the character of theborate; and that by proper control of such reaction it is possible toproduce compositions which are remarkably useful as functional fluids oradditives, for instance corrosion inhibiting additives. Ethylene anddiethylene glycols are preferred because of their ability to combinewith greater concentrations of borate.

We have found that when the described organic glycol and boratereactants are mixed and heat reacted in a mole ratio of glycol to borateof from about three to one to about twelve to one, widely varyingquantities of water may be removed by evaporation and/or condensation.The water removed may approach, and in some instances may equal, themaximum water theoretically available from the reaction, i.e., the totalwater of hydration of the borate reactant plus one mole of water foreach mole of glycol. For example, where one mole of sodium tetraboratepentahydrate and moles of ethylene glycol are the reactants, it ispossible to remove by the reaction, moles of Water. This is shown by thefollowing equation thus:

One mole of Na B O -5H O-i-5 moles HOCH CH OH [(Na B O 5 (CH CH O) +10moles Hi0 A range of products may thus be produced depending upon theextent of water removal and varying typically from substantiallynon-adherent liquids that are viscous but readily pourable at roomtemperature, to brittle solids readily pourable at higher temperaturesat or below 100 C. and also soluble in organic fluids such as glycols orethers of glycols.

A more particular aspect of the present invention is concerned withcondensed compositions of the described type which are effectivelyhomogeneous liquidsat normalv v,

or moderately elevated temperatures and which are readily miscible withglycol and other fluids of the described type.

The products of the present invention are characterized by'the presenceof alkali metal or alkaline earth metal in a definite proportion to theboron, and are thereby distinguished from previously known condensationproducts of alcohols with boric acid, for example. The products are alsocharacterized by the initial presence of only one or two hydroxyl groupsper molecule of the initial organic compound, in contrast to previouslyknown reactions of alkali metal borates with polyfunctionalconfigurations containing more than two hydroxyl groups.

The products of the invention may be produced by stirring together solidalkali metal or alkaline earth metal tetraborate or metaborate and aglycol containing from two to six carbon atoms, inclusive, andsubjecting the mixture to elevated temperature and reduced pressure toremove water therefrom. At a temperature of about to 125 C., forexample, appreciable condensation of the reactants typically takes placein a few minutes, and the released water may be removed by maintaining apressure of 10 to 30 mm. of Hg. Condensation products may be prepared inthe same manner from a borate and a monoalkyl ether of a glycol, suchfor example, as diethylene glycol monoethyl ether containing a straightglycol in suflicient amount to carry the reaction, such as a commercialmonoalkyl ether containing ethylene glycol as a diluent.

A further feature of the presentinvention is the discovery that manycondensation products of the type described may be prepared withoutphysically removing water from the reaction mixture of borate andorganic compound. Such may be accomplished by employing a form of boratewhich is substantially or completely dehydrated, for example, anhydroussodium tetraborate. The water produced by condensation reaction of theborate and glycol is then apparently taken up by the borate-glycolcondensation complex.

The preferred compositions of the present invention for use as anadditive composition for glycol and other organic fluids and especiallywhere corrosion inhibiting is desirable are those which do not containmore water than corresponds to the water formed in condensation of theborate and glycol or glycol derivatives, for example, ethers of glycolsmade by processes which may or may not involve the formation of glycolsas an intermediate. Such compositions result when the initial reactantsdo not contain any water of hydration, or when an amount of water atleast equal to the water of hydration of the borate reactant is removedin preparation of or formation of the condensed composition.

We have discovered that it is possible to prepare condensed productswhich contain less than the preferred maximum water content justdescribed and which are nevertheless readily pourable liquids at aconvenient working temperature not exceeding about C. Although theminimum water content for such a liquid product varies considerably withthe particular initial ingredients chosen, and with the proportions ofinitial reactant ingredients combined, and the temperatures andpressures employed in the condensation reaction, we have found ingeneral that liquid products are obtainable if the water removed doesnot exceed the sum of any water of hydration of the initial boratereactant and approximately half of the condensation water correspondingto complete condensation of the borate reactant and the glycol or glycolderivative. Such complete condensation normally releases one mole ofwater per mole of glycol, or 0.5 mole of water per mole of monoalkylether of a glycol.

By controlling the reaction within the limits indicated, it is possibleto produce additive compositions containing a minimum amount of water aspart of the borateglycol complex and yet having physical properties thatpermit accurate and convenient handling and complete dispersal in theorganic fluids such as glycols to be treated.

A full understanding of the invention and of its further objects andadvantages will be had from the following examples of specific productsand of typical processes by which they may be produced. Those examplesare intended only for illustration of the invention and not as alimitation upon its scope.

Example 1.-Sodium tetraborate pentahydrate and diethylene glycol weremixed in' a molar ratio of 1:9 and heated to about 113 C. The pressurewas reduced to 18 mm. of Hg and released water was collected in acondenser cooled with ice water. The total water thus collectedcorresponded to the 5 moles of water of hydration of the tetraborate andapproximately 0.5 mole of period of 15 minutes.

not was filtered at about 90 C.- through a coarse fritted glass filter.The product was a pale yellow liquid, nearly immobile at roomtemperature, but pourable when warmed to about 30 C. It was found onanalysis to contain 4.08% boron and 4.33% sodium and had a density of1.28 at 25 C.

Example 2.Sodium tetraborate pentahydrate was mixed with ethylene glycolin a molar ratio of 1:6. Water was removed at a pressure of about 40 mm.of Hg and at a temperature of 75 to 110 C. during a The total amount ofwater removed corresponded to the 5 moles of water of hydration of theborate plus 0.2 mole of water per mole of glycol. In this preparationthe borate dissolved completely, and a clear liquid product was obtainedwithout filtration. The viscosity of the condensed product was similarto that of Example 1, and was 2,300 centistokes at 82 C. The product wasfound on analysis to contain 7.98% boron and 8.48% sodium and had adensity of 1.41 at 25 C.

Example 3.Sodium tetraborate pentahydrate was mixed with triethyleneglycol in a molar ratio of 1 to 12. An amount of water corresponding tothe initial water of hydration of the borate was removed at 100 to 125C. and a pressure of 6 to 20 mm. of Hg. After filtration, the condensedproduct was a clear, readily pourable liquid, miscible in allproportions in ethylene glycol, diethylene glycol and diethylene glycolmonoethyl ether such as Carbitolf It had a density of 1.20 at 25 C. anda viscosity of 3,500 eentistokes at 82 C., and was found to contain2.14% boron and 2.27% sodium.

Example 4.--Sodium tetraborate pentahydrate was mixed with hexyleneglycol (Z-methyl 2,4-pentane-diol) in a molar ratio of about 1 to 7.5.An amount of water was removed corresponding to only the initial waterof hydration of the tetraborate. In this and in subsequent Examples 5-7,9, 10 and 12-l6 water removal was carried out at temperatures in therange from 75 to 120 C. and at pressures in the range from 15 to 30 mm.of Hg. After filtration at elevated temperature, the condensed productwas a white solid at room temperature, melting at about 35 C.

Example 5.4odium tetraborate pentahydrate was mixed with 2,3-butanediolin a molar ratio of 1 to 12 at a temperature of approximately 100 C.,and an amount of water was removed at reduced pressure corresponding tothe initial water of hydration of the tetraborate and 0.25 mole of waterper mole of glycol. The resulting condensed product was a translucentsyrup which was found on analysis to contain 3.68% boron and 3.92%sodium. r n.

Example 6.-Thc procedure of Example 5 was repeated, but replacing the2,3-butanediol .by 1,4-butanediol and removing only an amount of watercorresponding to the water of hydration of the sodium tetraboratepentahydrate. The condensed product was a clear readily pourable liquid.

Example 7. -Condensation products of the type described may be made inthe manner described using as the borate reactant sodium tetraborate ofother degrees of hydration. For example, sodium tetraborate decahydratewas mixed with diethylene glycol in a molar ratio of 1 to 9. Afterremoval of an amount of water corresponding to the initial water ofhydration of the borax, the condensed product was a colorless liquidwith a density of 1.23 and a viscosity of 14,000 centistokes at 25 C. Itwas miscible in all proportions in ethylene glycol, diethyleneglycol andCarbitol. Condensation products of sodium tetraborate and ethyleneglycol, triethylene glycol, butanediols and hexylene glycol can also beprepared using the sodium tetraborate decahydrate reactant.

Example 8.-Anhydrous sodium tetraborate was stirred in ethylene glycolin a molar ratio of l to 6 at a temperature of approximately 100 C.without physical re- 'moval of water. 'Theresulting condensedproduct'-wa s a liquid, nearly immobile at room temperature, but pourable whenwarm. The water released by condensation of the tetraborate and glycolwas apparently taken up as part of the borate-glycol complex.

Example 9.Anhydrous sodium tetraborate was stirred with ethylene glycolin a molar ratio of 1 to 6, and approximately 0.5 mole of water per moleof glycol was removed in the manner already described. The resultingcondensed product was a solid glassy material containing 8.28% boron and8.68% sodium. When heated to nearly 100 C. it became a pourable fluid.

Example 10.-The procedure of Example 9 was repeated, but with a molarratio of anhydrous borax to ethylene glycol of 1 to 9. Removal of 0.5mole of water per mole of glycol yielded, after filtration, a condensedproduct which was a clear syrup containing 6.25% boron and 6.62% sodium.

Example 1I.Anhydrous sodium tetraborate was mixed with 2,3-butanediol ata molar ratio of 1 to 12 at a temperature of about 100 C. The resultingcondensed product was a clear liquid, which was found to contain 3.25%boron and 3.48% sodium.

Example I2.-C0ndensed products in accordance with the invention may beprepared from borates having a wide range of molar ratio of metal to B 0In particular, such products may be prepared from metaborates, forexample, as well as from tetraborates. Condensed products can also beprepared from mixtures of borates, such as mixtures of tetraborates andmetaborates. For example, sodium metaborate (Na B O -4H O) was mixedwith ethylene glycol at a molar ratio of 1 to 9 and water was removed atapproximately 100 C. and at reduced pressure. The total water removedcorresponded to the initial water of hydration of the metaborate and0.33 mole of water per mole of glycol. A condensed product was obtainedwhich was a viscous but mobile colorless liquid at room temperature andwhich was found to contain 3.64% boron and 7.40% sodium.

Example I3.-The procedure of Example 12 was repeated, but employingsodium metaborate and ethylene glycol at a molar ratio of about 1 to 6.6and removing an amount of water corresponding to only the initial waterof hydration of the metaborate. The resulting condensed product, afterfiltration at to C., was a viscous but mobile pale yellow liquid whichwas found to contain 4.46% boron and 9.03% sodium.

Example 14.--Products in accordance with the invention may be preparedfrom glycols and any desired alkali metal borate. For example, potassiumtetraborate (K B O -4H O) was mixed with diethylene glycol at a molarratio of 1 to 9, and an amount of water was removed corresponding to theinitial water of hydration of the tetraborate and 0.5 mole of water permole of glycol. The resulting condensed product was a transparent syrup,found to contain 397% boron and 7.03% potassium. Condensation productscan also be made with potassium tetraborate or metaborate and otherglycols, including ethylene glycol, triethylene glycol, butanediols andhexylene glycol.

Example l5.Condensation products in accordance with the invention canalso be prepared from alkaline earth metal borate glycols of thedescribed type. As an example, calcium metaborate (CaB O -6H O) wasmixed with ethylene glycol at a molar ratio of approximately 1 to 12. Anamount of water was removed substantially corresponding to the waterinitially present as water of hydration of the metaborate. product was aviscous but mobile pale yellow liquid and was found to contain 2.37%boron and 4.1% calcium.

Example I6.Condensation products can be made not only with the describedglycols, but also with monoalkyl ethers of such glycols which contain aminor proportion of glycol. Such condensation products include those Theresulting condensed -made with the monomethyl ether of diethylene glycol{CH OCH CH CH CH OHL the monoethyl ether of diethylene glycol [CH CH OCHCH OCH CH OH], the monoispropyl ether of diethylene glycol CH COCH CH OCH CH OH] and the monobutyl ether of diethylene glycol [CH CH CH CH 0CHCH OCH CH OH] --For example commercial diethylene glycol monoethyl ethercontaining some ethylene glycol as a diluent was mixed with sodiumtetraborate pentahydrate at a molar ratio of tetraborate to ether equalto l to 6.55. An :amount of water corresponding to the initial water of'hydration of the tetrahorate was removed at elevated temperature andreduced pressure. The resulting condensed product was a clear liquid andwas found to contain 3.08% boron and 3.26% sodium.

Most of the illustrative condensation products that have been describedare liquid at room temperature, and all are liquid and readily pourableat a working temperature that does not exceed about 100 C. Moreover, thedescribed liquid compositions are found to be readily miscible inconcentrations up to at least 25% by weight and usually in allproportions, in glycols and glycol derivatives such as ethers of glycolthat are ordinarily employed in hydraulic and coolant fluids, includingin particular ethylene glycol, diethylene glycol and diethylene glycolmonoethyl ether.

It is of particular interest that in preparation of a condensed productof the described type from a hydrated borate and a glycol or glycolderivative, water removal typically proceeds smoothly and withoutdiscontinuity or other abnormality through the point which correspondsto complete removal of any initial water of hydration. Moreover, so faras has been ascertained, the nature of the condensed product isindependent of the degree of hydration of the initial ingredients,provided, of course, that the amount of water removed is adjustedcorrespondingly.

'We have discovered that condensed compositions of the type describedare particularly valuable for improving the properties of many types oforganic fluids in which they are readily miscible. As an example,addition to such fluids of suitable proportions of the condensedcompositions of the invention has been found to inhibit corrosion atleast as effectively as a corresponding amount of a hydrated alkalimetal or a hydrated alkaline earth metal borate, while avoiding thedisadvantages previously associated with use of the latter compounds. Inparticular, use of the compounds of the invention greatly reduces oreliminates the introduction into the organic fluid of water such as istypically contained as water of hydration in those borates that wereotherwise suitable for the described use. Moreover, the difficulties ofob taining complete solution of a solid additive are entirely avoided byutilizing the compositions of the invention, which are fluid either atroom temperature or at a moderately elevated working temperature. Suchfluid compositions can be metered accurately and conveniently, and arereadily miscible in many organic fluids in which solid borates areeither insoluble or only very slowly soluble. The most desirableconcentration of the additive composition in the glycol fluids, althoughvarying con siderably with many factors, such as the proportion ofborate in the additive composition and the type of service for which thetreated glycol fluids are intended, is usually between about 0.2% andabout 10% by weight. Hydraulic fluids made from' higher polyglycols mayalso be effectively treated in the same manner to render themsubstantially non-corrosive.

The following are typical examples of applications utilizing theadditive composition of the invention:

- Example 17.-A brake fluid in which corrosion was inhibited effectivelyby the additive composition of the invention was prepared by mixingsubstantially equal volumes of ethylene glycol monobutyl ether,diethylene glycol monoethyl ether and a polyalkylene glycol lubricantsuch as Ucon" 50-HB-66O made by Carbide and Carbon Chemical Company andadding to this mixture with agitation from about 1% to about 5% byweight of the total brake fluid composition of an additive compositionof the invention made in accordance with Example 1.

Example I8.--A hydraulic fluid was prepared by mixing by volume 10 partsof ethylene glycol, 70 parts of dipropylene glycol methyl ether and 20parts of polyalkylene glycol lubricant such as polyglycol 15-200 made byDow Chemical Company and adding to this mixture with agitation fromabout 1% to about 5% by weight of the total fluid composition of theadditive composition made in accordance with Example 14. The resultantfluid has effective corrosion inhibiting properties.

Example I 9.A hydraulic fluid was prepared by mixing by volume 60 partsof diethylene glycol monoethyl ether, 10 parts of diethylene glycolmonobutyl ether, 25 parts of a polyalkylene glycol lubricant such asUcon 50-HB-660, 3 parts diethylene glycol and 2 parts of the additivecomposition made in accordance with Example 14. The resultant fluid haseffective corrosion inhibiting properties and is particularly applicableto uses as a hydraulic window lift fluid or a brake fluid.

Example 20.In certain exceptional cases it may be desired to directlyproduce the functional organic fluid composition of the inventionwithout employing the above-described additive compositions. This can bedone by reacting such ratios of .borate compounds and glycols and theirderivatives described above such that the resultant composition willitself be one having the relative molar ratio of organic compound toborate compound obtained for example in a composition such as describedin Example 17 wherein an additive composition of the invention iscombined with an organic fluid. Effective results are typicallyobtainable with a molar ratio of organic compound to borate compoundbetween 50 and 400. This procedure is not however preferred since adisadvantage of it is the possible loss of organic fluids of the glycoltype during processing and the need for processing large volumes offluid by a continuous process or by large processing equipment.

Thus equal parts by volume of diethylene glycol monobutyl ether,diethylene glycol monoethyl ether and a polyalkylene glycol such as Ucon50-HB-660 and one percent by weight of these, of sodium tetraboratedecahydrate were mixed and heated to a temperature between 150 and 175C. under a vacuum of approximately 10 inches of mercury, by a continuousprocess until approximately all of the water of hydration of the boratereactant was evaporated. The resultant product was one that could beused directly as a hydraulic fluid and had corrosion resistantproperties. It has a molar ratio of organic compound to borate compoundof approximately 200 to 1 and is a readily pourable liquid at normalatmospheric temperatures.

Other modes of applying the principle of the invention may be employedprovided the features stated in any of the following claims or theequivalent of such be employed.

l wf therefore, particularly point out and claim as our invention:

1. A substantially water-free organic hydraulic fluid compositioninhibited against metal corrosion. consisting essentially of at leastone material selected from the group consisting of glycols, ethers ofglycols and mixtures thereof and from about 0.2 to about 10% by weightof a corrosion inhibiting additive, said additive consisting essentiallyofacondensation-product of an organic compound and a borateeompound,said organic compound being selected from :the class consisting ofglycols con- 9 taining from 2 to 6 carbon atoms and mixtures of glycolscontaining from 2 to 6 carbon atoms with monoalkyl ethers of glycolscontaining from 2 to 6 carbon atoms, the alkyl group of said monoalkylethers containing from 1 to 4 carbon atoms, said borate compound beingselected from the group consisting of alkali metal tetraborates andmetaborates and alkaline earth metal tetraborates and metaborates, themolar ratio of organic compound to borate compound in said condensationproduct being from about 3:1 to about 12:1, the water content of saidcondensation product not substantially exceeding the water formed incondensation of said compounds, and said condensation product being asubstantially homogeneous and readily pourable liquid at a temperatureless than about 100 C.

2. A corrosion-inhibited hydraulic brake fluid composition consistingessentially of about equal volumes of ethylene glycol monobutyl ether,diethylene glycol monoethyl ether, a polyalkylene glycol and from about1 to about 5% by weight of the condensation product of an organiccompound and a borate compound, said organic compound selected from theclass consisting of glycols containing from two to six carbon atoms andmixtures of glycols containing from two to six carbon atoms withmonoalkyl ethers of glycols containing from two to six carbon atoms, thealkyl group of said monoalkyl ethers containing from one to four carbonatoms, said borate compound selected from the group consisting of alkalimetal tetraborates and metaborates and alkaline earth metal tetraboratesand metaborates, the molar ratio of organic compound to borate compoundin said condensation product being from about three to one to abouttwelve to one, the water content of said condensation product notsubstantially exceeding the water formed in condensation of saidcompounds, and said condensation product being a substantiallyhomogeneous and readily pourable liquid at a temperature less than about100 C.

3. A corrosion-inhibited hydraulic brake fluid composition consistingessentially by volume of about parts of ethylene glycol, 70 parts ofdipropylene glycol methyl ether, 20 parts of a polyalkylene glycol andfrom about 1 to about 5% by weight of the condensation product of anorganic compound and a borate compound, said organic compound selectedfrom the class consisting of glycols containing from two to six carbonatoms and mixtures of glycols containing from two to six carbon atomswith monoalkyl ethers of glycols containing from two to six carbonatoms, the alkyl group of said monoalkyl ethers containing from one tofour carbon atoms, said borate compound selected from the groupconsisting of alkali metal tetraborates and metaborates and alkalineearth metal tetraborates and metaborates, the molar ratio of organiccompound to borate compound in said condensation product being fromabout three to one to about twelve to one, the water content of saidcondensation product not substantially exceeding the water formed incondensation of said compounds, and said condensation product being asubstantially homogeneous and readily pourable liquid at a temperatureless than about 100 C.

4. A corrosion-inhibited hydraulic brake fluid composition consistingessentially by volume of about 60 parts of diethylene glycol monoethylether, 10 parts of diethylene glycol monobutyl ether, 25 parts of apolyalkylene glycol and 2 parts of the condensation product of anorganic compound and a borate compound, said organic compound selectedfrom the class consisting of glycols containing from two to six carbonatoms and mixtures of glycols containing from two to six carbon atomswith monoalkyl ethers of glycols containing from two to six carbonatoms, the alkyl group of said monoalkyl ethers containing from one tofour carbon atoms, said borate compound selected from the groupconsisting of alkali metal tetraborates and metaborates and alkalineearth metal tetraborates and metaborates, the molar ratio of organiccompound to borate compound in said condensation product being fromabout three to one to about twelve to one, the water content of saidcondensation product not substantially exceeding the water formed incondensation of said compounds, and said condensation product being asubstantially homogeneous and readily pourable liquid at a temperatureless than about C.

5. A corrosion-inhibited organic coolant fluid suitable for use inaqueous heat exchange systems consisting essentially of a materialselected from the class consisting of glycols, ethers of glycols andmixtures thereof and from about 0.2 to about 10% by weight of acorrosioninhibiting additive, said additive consisting essentially of acondensation product of an organic compound and a borate compound, saidorganic compound being selected from the class consisting of glycolscontaining from 2 to 6 carbon atoms and mixtures of glycols containingfrom 2 to 6 carbon atoms with monoalkyl ethers of glycols containingfrom 2 to 6 carbon atoms, and the alkyl group of said monoalkyl etherscontaining from 1 to 4 carbon atoms, said borate compound being selectedfrom the group consisting of alkali metal tetraborates and metaboratesand alkaline earth metal tetraborates and metaborates, the molar ratioof organic compound to borate compound in said condensation productbeing from about 3:1 to about 12:1, the water content of saidcondensation product not substantially exceeding the water formed incondensation of said compounds, and said condensation product being asubstantially homogeneous and readily pourable liquid at a temperatureless than about 100 C.

6. The method of operating a fluid hydraulic system which comprisestransmitting power in said hydraulic system by the use of asubstantially non-corrosive organic hydraulic fluid, said fluidconsisting essentially of a material selected from the group consistingof glycols, ethers of glycols, mixtures of glycols, mixtures of ethersof glycols, and mixtures of glycols and ethers of glycols, and fromabout 0.2 to about 10% by weight of the condensation product of anorganic compound and a borate compound, said organic compound beingselected from the class consisting of glycols containing from two to sixcarbon atoms and mixtures of glycols containing from two to six carbonatoms with monoalkyl ethers of glycols containing from two to six carbonatoms, the alkyl group of said monoalkyl ethers containing from one tofour carbon atoms, said borate compound being selected from the groupconsisting of alkali metal tetraborates and metaborates and alkalineearth metal tetraborates and metaborates, the molar ratio of organiccompound to borate compound in said condensation product being fromabout three to one to about twelve to one, the water content of saidcondensation product not substantially exceeding the water formed incondensation of said compounds, and said condensation product being asubstantially homogeneous and readily pourable liquid at a temperatureless than about 100 C.

References Cited inthe file of this patent UNITED STATES PATENTS2,084,261 Boughton June 15, 1937 2,345,586 Clark Apr. 4, 1944

1. A SUBSTANTIALLY WATER-FREE ORGANIC HYDRAULIC FLUID COMPOSITIONINHIBITED AGAINST METAL CORROSION, CONSISTING ESSENTIALLY OF AT LEASTONE MATERIAL SELECTED FROM THE GROUP CONSISTING OF GLYCOLS, ETHERS OFGLYCOLS AND MIXTURES THEREOF AND FROM ABOUT 0.2 TO ABOUT 10% BY WEIGHTOF A CORROSION INHIBITING ADDITIVE, SAID ADDITIVE CONSISTING ESSENTIALLYOF A CONDENSATION PRODUCT OF AN ORGANIC COMPOUND AND A BORATE COMPOUND,SAID ORGANIC COMPOUND BEING SELECTED FROM THE CLASS CONSISTING OFGLYCOLS CONTAINING FROM 2 TO 6 CARBON ATOMS AND MIXTURES OF GLYCOLSCONTAINING FROM 2 TO 6 CARBON ATOMS WITH MONOALKYL ETHERS OF GLYCOLSCONTAINING FROM 2 TO 6 CARBON ATOMS, THE ALKYL GROUP OF SAID MONALKYLETHERS CONTAINING FROM 1 TO 4 CARBON ATOMS, SAID BORATE COMPOUND BEINGSELECTED FROM THE GROUP CONSISTING OF ALKALI METAL TETRABORATES ANDMETABORATES AND ALKALINE EARTH METAL TETRABORATES AND METABORATES, THEMOLAR RATIO OF ORGANIC COMPOUND TO BORATE COMPOUND IN SAID CONDENSATIONPRODUCT BEING FROM ABOUT 3:1 TO ABOUT 12:1, THE WATER CONTENT OF SAIDCONDENSATION PRODUCT NOT SUBSTANTIALLY EXCEEDING THE WATER FORMED INCONDENSATION OF SAID COMPOUNDS, AND SAID CONDENSATION PRODUCT BEING ASUBSTANTIALLY HOMOGENEOUS AND READILY POURABLE LIQUID AT A TEMPERATURELESS THAN ABOUT 100*C.
 6. THE METHOD OF OPERATING A FLUID HYDRAULICSYSTEM WHICH COMPRISES TRANSMITTING POWER IN SAID HYDRAULIC SYSTEM BYTHE USE OF A SUBSTANTIALLY NON-CORRISIVE ORGANIC HYDRAULIC FLUID, SAIDFLUID CONSISTING ESSENTIALLY OF A MATERIAL SELECTED FROM THE GROUPCONSISTING OF GLYCOLS, ETHERS OF GLYCOLS, MIXTURES OF GLYCOLS, MIXTURESOF ETHERS OF GLYCOLS, AND MIXTURES OF GLYCOLS AND ETHERS OF GLYCOLS, ANDFROM ABOUT 0.2 TO ABOUT 10% BY WEIGHT OF THE CONDENSATION PRODUCT OF ANORGANIC COMPOUND AND A BORATE COMPOUND, SAID ORGANIC COMPOUND BEINGSELECTED FROM THE CLASS CONSISTING OF GLYCOLS CONTAINING FROM TWO TO SIXCARBON ATOMS AND MIXTURES OF GLYCOLS CONTAINING FROM TWO TO SIX CARBONATOMS WITH MONOALKYL ETHERS OF GLYCOLS CONTAINING FROM TWO TO SIX CARBONATOMS, THE ALKYL GROUP OF SAID MONOALKYL ETHERS CONTAINING FROM ONE TOFOUR CARBON ATOMS, SAID BORATE COMPOUND BEING SELECTED FROM THE GROUPCONSISTING OF ALKALI METAL TETRABORATES AND METABORATES AND ALKALINEEARTH METAL TETRABORATES AND METABORATES, THE MOLAR RATIO OF ORGANICCOMPOUND TO BORATE COMPOUND IN SAID CONDENSATION PRODUCT BEING FROMABOUT THREE TO ONE TO ABOUT TWELVE TO ONE, THE WATER CONTENT OF SAIDCONDENSATION PRODUCT NOT SUBSTANTIALLY EXCEEDING THE WATER FORMED INCONDENSATION OF SAID COMPOUNDS, AND SAID CONDENSATION PRODUCT BEING ASUBSTANTIALLY HOMOGENEOUS AND READILY POURABLE LIQUID AT A TEMPERATURELESS THAN ABOUT 100*C.